Add search subcommand
Problem to solve
As a user, I want to search from the commandline. I.e. I want to know which projects include a certain filename, and include the search results in text format. Search via web is possible, but you can't easily copy and paste the search results.
Proposal
Add a search subcommand which works the same as the Web seach function. I.e.
glab search "filename:README.md"